Previously, some studies have suggested possible links between farming and agriculture-related pesticide exposures and autoimmune disease. Christine G. Parks, from the National Institute for Environmental Health Science (North Carolina, USA), and colleagues studied non-occupational insecticide exposures and the risk of rheumatoid arthritis or systemic lupus erythematosus (SLE).  Analyzing data collected on 76,861 postmenopausal women enrolled in the Women's Health Initiative Observational Study, ages 50 to 79 years, the researchers found that those who personally mixed or applied insecticides, primarily for in-home use, had an adjusted hazard ratio for rheumatoid arthritis or systemic lupus erythematosus of 1.57, as compared to women who reported no exposure to the chemicals.  Importantly, the adjusted hazard ratio rose to 1.97 with 20 or more years of exposure, and to 2.04 with six or more exposures per year. Writing that: “Compared with never used, personal use of insecticides was associated with increased [rheumatoid arthritis /systemic lupus erythematosus] risk, with significant trends for greater frequency ,” the team concludes that: “These results suggest residential and work place insecticide exposure is associated with the risk of autoimmune rheumatic diseases in postmenopausal women. Although these findings require replication in other populations, they support a role for environmental pesticide exposure in the development of autoimmune rheumatic diseases.”